A reductionist approach to HIV research

George Kassiotis, from the Division of Immunoregulation at MRC National Institute for Medical Research, worked with a team of researchers to create mice whose CD4+ T cells, the cells eliminated by HIV infection, commit a kind of suicide upon activation.

He said, “Although these mice do not fully reproduce every aspect of human HIV-associated immune dysfunction, they do approximate two key immune alterations – CD4+ T cell immune deficiency and generalized immune activation. Further definition of the precise balance between CD4+ T cell killing and immune activation and deficiency will be vital to our understanding of the pathogenesis of immune deficiency virus infection.”

The CD4+ T cells in the researchers' mice were engineered to express a toxin, diphtheria toxin A fragment, upon activation. This genetic self-destruct system causes the death of the cell within 48 hours. The resultant loss of activated immune cells caused the mice to exhibit symptoms with some similarities to those of immunodeficiency virus infection. There are clear differences between the mouse and a human infected with HIV, however, such as the fact that the ongoing depletion of nearly all activated CD4+ T cells in the mice does not result in the progressive erosion of naïve and memory CD4+ T cells seen during HIV infection. None-the-less, insights gained from this reductionist model can only help our understanding of human disease. In a commentary on the work in the same issue of Journal of Biology, experts on T cells and HIV at the US National Institutes of Health comment that the mouse will be as useful for its differences from human infection as it will for its similarities.

Notes to Editors:

1. Generalized immune activation as a direct result of activated CD4+ T cell killing
Rute Marques, Adam Williams, Urszula Eksmond, Andy Wullaert, Nigel Killeen, Manolis Pasparakis, Dimitris Kioussis and George Kassioti

Journal of Biology 2009, 8:93 doi:10.1186/jbiol194

2. Journal of Biology is an international journal that publishes biological research articles of exceptional interest or importance, together with associated commentary. Original research articles that are accepted for publication are published in full on the web within two weeks, and are immediately made freely available to all. Articles from the full spectrum of biology are appropriate for consideration, provided that they are of substantial interest or importance, or are likely to have a significant and lasting impact on their field.

3. BioMed Central (http://www.biomedcentral.com/) is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.